Composite heavy-duty mechanism element and method of making the same

ABSTRACT

A composite mechanism element, such as a bevel pinion (FIGS. 1 to 6 inclusive), or the inner race of a tapered roller bearing (FIGS. 7 to 10 inclusive and 16) has its working or load-bearing portion or portions composed of sintered powdered highperformance alloy while its supporting portion not subjected to concentrated or heavy loads, is made of a base metal, such as sintered powdered iron. The toothed outer load-bearing portion of the composite bevel pinion (FIG. 6) and the hollow frusto-conical inner supporting portion (FIGS. 10 to 15) are separately briquetted from high performance alloy powder and low performance metal powder respectively and separately sintered after which the low performance inner supporting portion is pressed into the high performance toothed outer portion so as to be inseparably secured thereto. In the inner race (FIG. 15) of the composite tapered roller bearing (FIG. 16) the low-performance and high-performance portions of the inner race are separately compacted in dies in a briquetting press to form briquettes which are separately sintered and thereafter are pressed together in an assembling operation which causes the high performance and low performance portions of each race to be inseparably secured to one another. The composite outer race is formed by arranging base metal powder and high performance alloy powder in abutting zones in an annular cavity of a briquetting press die and compressing them to form a composite briquette which is then sintered and afterward deformed in a forging die into its final annular shape. The resulting composite sintered powdered mechanism elements are of much lower material cost than corresponding mechanism elements formed of high performance alloy throughout yet perform satisfactorily and have sufficient strength and durability for most purposes. The tapered roller bearing races (FIG. 9) or the bevel pinion (FIG. 15) may be used as they are if of satisfactory density for their intended uses, or they may be further densified by being subjected to an additional hot forging operation with the article sintered thereafter if deemed necessary.

United States atent Dunn et al.

[ COMPOSITE HEAVY-DUTY MECHANISM ELEMENT AND METHOD OF MAKING THE SAME[72 Inventors: William M. Dunn, Farmington; Myron C.

Sarnes, Northville, both of Mich.

Federal-Mogul Corporation, S outhfield, Mich.

22 Filed: Dec. 4, 1970 21 Appl.No.: 95,299

[73] Assignee:

Primary Examiner-Leonard I-I. Gerin Attorney-Barthel & Bugbee [57]ABSTRACT A composite mechanism element, such as a bevel pinion (FIGS. 1to 6 inclusive), or the inner race of a tapered roller bearing (FIGS. 7to 10 inclusive and 16) has its working or load-bearing portion orportions composed of sintered powdered high-performance alloy while itssupporting portion not subjected to concentrated or heavy loads, is madeof a base metal, such as sintered powdered iron. The toothed outerload-bearing portion of the composite bevel pinion (FIG. 6) and thehollow frusto-conical inner supporting portion (FIGS. 10 to 15) areseparately briquetted from high performance alloy powder and lowperformance metal powder respectively and separately sintered afterwhich the low performance inner supporting portion is pressed into thehigh performance toothed outer portion so as to be inseparably securedthereto. In the inner race (FIG. 15) of the composite tapered rollerbearing (FIG. 16) the low-performance and high-performance portions ofthe inner race are separately compacted in dies in a briquetting pressto form briquettes which are separately sintered and thereafter arepressed together in an assembling operation which causes the highperformance and low performance portions of each race to be inseparablysecured to one another. The composite outer race is formed by arrangingbase metal powder and high performance alloy powder in abutting zones inan annular cavity of a briquetting press die and compressing them toform a composite briquette which is then sintered and afterward defonnedin a forging die into its final annular shape. The resulting compositesintered powdered mechanism elements are of much lower material costthan corresponding mechanism elements formed of high performance alloythroughout yet perform satisfactorily and have sufficient strength anddurability for most purposes. The tapered roller bearing races (FIG. 9)or the bevel pinion (FIG. 15) may be used as they are if of satisfactorydensity for their intended uses, or they may be further densified bybeing subjected to an additional hot forging operation with the articlesintered thereafter if deemed necessary.

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11% INVENTORS WILLIAM M, DUNN MYRON C. SARNES COMPOSITE HEAVY-DUTYIWECl-IANISM ELEMENT AND METHOD OF MAKING THE SAME BACKGROUND ANDSUMMARY OF INVENTION Heavy-duty mechanism elements which duringoperation are subjected to heavy loads or stresses have hitherto beenformed from high-cost nickel-content alloys which in themselves are veryexpensive and which consequently cause such mechanism elements madetherefrom to be likewise very expensive. In actual fact, however, only aportion of such mechanism elements is ordinarily subjected toconcentrated heavy loads, torques or stresses which require the use ofhigh performance alloys, yet the formation of the entire mechanismelement therefrom has hitherto been required and has been of excessivelyhigh cost of production not only from the high cost of the alloysthemselves but also from the expensive forging operations required inits production.

The present invention overcomes these prior disadvantages by providingheavy-duty mechanism elements, such as bevel pinions and the inner racesof tapered roller bearings wherein the working portions subjected toheavy or concentrated loads, torques or other stresses are formed fromsintered powdered high-performance alloys whereas the remainingsupporting portions thereof are formed from separately briquettedsintered powdered low-performance metals. The two portions, thusseparately produced, are then pressed tightly into inseparableengagement with one another. As a result, the amount of high-costhigh-performance alloy in each such mechanism element is greatly reducedin comparison to the forging of the same mechanism element from solidhighperformance alloys throughout with a corresponding reduction in theultimate cost of the finished mechanism element as well as aconservation of the nickel and other expensive metals which go into suchalloys as components thereof. At the same time, however, the heavy-dutyload-bearing performance capability of the composite mechanism elementis preserved without entailing the high cost previously accompanying theproduction of forged unitary high performance mechanism elements of highperformance alloys throughout. In the drawings,

FIG. 1 is a central vertical section through the die cavity of abriquetting press showing the positions of the various parts at thecommencement of briquetting the outer heavy-duty or working component ofthe heavy-duty bevel pinion shown in FIG. 6;

FIG. 2 is a view similar to FIG. 1 but showing the positions of thevarious parts at the termination of the briquetting operation;

FIG. 3 is a central vertical section through the die cavity of abriquetting press showing the positions of the parts at the commencementof the briquetting operation of the inner or supporting or hub componentof the bevel pinion shown in FIG. 6;

FIG. 4 is a view similar to FIG. 3 but showing the positions of theparts at the termination of the briquetting operation;

FIG. 5 is a central vertical section through the inner and outercomponents for the bevel pinion shown in FIG. 6, at the commencement ofthe assembling operation for uniting said outer and inner components;

FIG. 6 is a central vertical section through the composite heavy-dutybevel pinion formed in the manner shown in FIGS. to 14 inclusive, withthe dotted lines indicating the roots of the teeth thereon;

FIG. 7 is a central vertical section through the die cavity of abriquetting press, showing the formation of the inner component of thecomposite heavy-duty inner race of FIG. 10, used in the heavy-dutytapered roller bearing unit shown in FIG. 16;

FIG. 8 is a central vertical section through the die cavity of abriquetting press, showing the formation of the outer heavydutycomponent of the composite heavy-duty inner race for the tapered rollerbearing unit of FIG. 16;

FIG. 9 is a central vertical section through the composite heavy-dutyinner race of FIG. 10, employing the inner and outer components of FIGS.7 and 8, prior to the machining of the annular roller path channeltherein; 7

FIG. 10 is a view similar to FIG. 9 with the inner race before machiningshown in dotted lines and after such machining shown in solid lines;

FIG. 1 1 is a central vertical section through a composite sinteredpowdered metal blank of high-performance alloy powder inside andlow-performance metal powder outside prior to deformation into the outerrace of a heavy-duty tapered roller bearing unit;

FIG. 12 is a central vertical section through the die cavity of a pressshowing in dotted lines the blank of FIG. 11 and in solid lines the sameblank after deformation into a composite heavy-duty outer race for thetapered roller bearing unit shown in FIG. 16;

FIG. 13 is a central vertical section through a modified compositesintered powdered metal blank of high-performance alloy powder above andlow-performance metal powder below, prior to deformation into the sameouter race for the same heavy-duty tapered roller bearing unit shown inFIG. 16;

FIG. 14 is a central vertical section through the die cavity of a presssimilar to that shown in FIG. 12, but showing in dotted lines the blankof FIG. 13 and in solid lines the same blank after deformation into thesame composite heavy-duty outer race for the same tapered roller bearingunit shown in FIG. 16;

FIG. 15 is a central vertical section through the composite outer raceformed as shown in FIGS. 11 and 12 or as in FIGS. 13 and 14; and

FIG. 16 is a central vertical section through a tapered roller bearingunit employing the composite heavy-duty inner and outer races formed inthe manner shown in FIGS. 7 to 15 inclusive.

Referring to the drawings in detail, FIGS. 1 to 6 inclusive show theadaptation of the present invention to the production of a compositeheavy-duty bevel pinion, generally designated 20 (FIG. 6) consisting ofan inner component 22 of low-performance sintered powdered metal, suchas sintered powdered iron, and a toothed outer component 24 ofhigh-performance sintered powdered metal alloy united thereto bypressure forging, as shown in FIG. 5. The outer or toothed component 24is formed by compressing a charge 26 (FIGS. 1 and 2) of ahighperformance powdered metal alloy in the generally frustoconical diecavity 28 of a briquetting die 30 having cylindrical upper and lowerbores 32 and 34 respectively joined by a frusto-conical bore 36.

Such a high-performance alloy may consist, for example, of the so-calledS.A.E. 4600 modified alloy, the standard composition of which isordinarily as follows:

0 to 0.25% Mn.

1.75 to 2.00% Ni. the remainder being Fe.

0.35 to 0.60% Mo.

The standard S.A.E. 4600 alloy of which the above is a The siliconcomponent is omitted in the modified alloy because silicon isdetrimental to the working life of a die set. It is ordinarily insertedin the above standard alloy in order to increase the fluidity of themolten alloy during the casting of intricate shapes.

The die 30 is mounted in a conventional briquetting press 38 having anupper outer tubular punch 40, a lower tubular punch 42, and an upperinner solid punch 44. The latter has upper and lower cylindricalportions 46 and 48 respectively interconnected by a frusto-conicalportion 50 and reciprocable in upper and lower inner bores 52 and 54within the tubular punches 40 and 42. The smaller diameter cylindricalportion 48 serves as a nose portion when the inner upper punch 44 israised together with the outer punch 40 so as to permit filling of thedie cavity 28 and at the same time prevent the powdered metal alloy inthe charge 28 from dropping into the otherwise open bore 54 within thelower tubular punch 42.

Prior to filling the die cavity 26 (FIG. 1) the outer upper tubularpunch 40 is retracted upward so as to uncover the top of the die cavity26. The latter is then filled with the charge 28 of high-performancepowdered metal alloy. The outer and inner upper punches 40 and 44 arethen moved downward in their respective bores 32 and 52, 54 from theposition of FIG. 1 to that of FIG. 2 while the lower tubular punch 42 ismoved upward in its respective bore 34 so as to compress the powderedmetal alloy charge 28 between the respective opposing annular endsurfaces 56 and 58 (FIG. 2) into a briquette 60, of the same dimensionsand proportions as the die cavity 26 and charge 28 at the end of thestroke of the punches 40, 42 and 44 as shown in FIG. 2. The briquette 60is then placed in a conventional sintering oven and sintered in aprotective atmosphere such as hydrogen at conventional sintering timesand temperatures well-known to those skilled in the powder metallurgyart. The workpiece, upon removal from the sintering oven aftersintering, becomes the outer or toothed heavyduty component 22 of thebevel pinion 20 shown in FIG. 6.

The inner component 22 of the bevel pinion 20 is similarly formed (FIGS.and 6) by placing a charge 62 of low-performance powdered base metal,such as powdered iron, in the generally frusto-conical die cavity 64 ina briquetting die 66 which is generally similar to the briquetting die30 of FIGS. 1 and 2 in that it has cylindrical upper and lower bores 68and 70 respectively joined by a frusto-conical bore 72. Reciprocablymounted in the upper and lower cylindrical bores 68 and 70 are upper andlower tubular punches 74 and 76. Mounted within the bores 78 and 80 inthe upper and lower tubular punches 74 and 76 is a cylindrical core rod82, the outer cylindrical surface 84 of which, along with the upper andlower cylindrical bores 68 and 70 and the frusto-conical bore 72constitute the die cavity 64.

In making the inner component 22, the upper punch 74 is retracted upwardso as to uncover the die cavity 64. The latter is then filled with thecharge 62 of low-performance powdered metal, such as powdered iron,whereupon the upper punch 74 is moved downward and the lower punch 86 ismoved upward so as to compress the powdered metal charge 62 betweentheir respective opposing annular end surfaces 86 and 88 respectivelyinto a briquette 90 (FIG. 4). The tubular upper punch 74 and lower punch76 are then moved upward to eject the briquette or compact 90 from thedie cavity 64. The briquette or compact 90 is then sintered in the samemanner as described above for the outer component 24, thereby becomingthe inner component 22. The inner component 22 of base metal is thenforced into the interior of the sintered high-performance alloy outercomponent 24 in a forging operation (FIG. 5), producing the compositeblank 92. The latter is then cut or ground with bevel teeth 94,whereupon the blank 92 becomes the finished bevel pinion 20 containingan inner bore 96 which is adapted to receive the shaft (not shown) uponwhich the bevel pinion 20 is to be mounted.

In FIGS. 7 to 16 inclusive there is shown the adaptation of the presentinvention to the production of a heavy-duty tapered roller bearing unit,generally designated 120 (FIG. 16) having a composite sintered powderedmetal inner race or cone 122 (FIG. and a composite sintered powderedmetal outer race or cup 124 (FIG. The inner race or cone 122 (FIG. 10)has an inner component 126 of sintered low-performance powdered basemetal, such as powdered iron, united by pressure forging with a sinteredhigh-performance powdered alloy outer component 128. The outer race orcup 124 (FIG. 9) has an outer component 130 of sintered low-performancepowdered base metal, such as powdered iron, and an inner component 132of sintered high-performance powdered alloy. The inner component 126 ofthe composite inner race 122 has a shaft bore 134 therein for receivingthe shaft (not shown) to be joumaled in the tapered roller bearing unit120, whereas the outer component 130 of the outer race 124 has agenerally cylindrical outer surface 136 adapted to be mounted in acylindrical bore or counterbore in the housing or other structure (notshown) in which the bearing unit 120 is to be mounted. Tapered bearingrollers 138 (FIG. 10) are mounted in the space between the outer andinner races 124 and 122.

The inner component 126 of the inner race 122 is formed by placing acharge (FIG. 1) of low-performance powdered base metal, such as powderediron, adapted, upon compression, to form a compact or briquette 140 inthe generally frusto-conical die cavity 142 of a briquetting die 144having cylindrical upper and lower bores 146 and 148 respectively joinedby a frusto-conical bore 150. The die 144 is mounted in a conventionalbriquetting press 152 having upper and lower tubular punches 154 and 156respectively reciprocably mounted in the die bores 146 and 148 andoperatively connected to reciprocable upper and lower platens (notshown) in the briquetting press 152. Fixedly mounted in the bores 158and 160 in the upper and lower tubular punches 154 and 156 is astationary core rod 162, the cylindrical outer surface 164 of which,with the bores 146, 150 and 148, the lower end 166 of the upper punch154 and the upper end 168 of the lower punch 156, defines the die cavity142. The charge of powdered base metal is then compacted into thebriquette 140 by moving the upper punch 154 downward and the lower punch156 upward to their final or end-of-stroke positions shown in FIG. 1,compressing the powdered base metal charge into the briquette 140 of thesame dimensions and proportions as the die cavity 142 at the end of thestrokes of the upper and lower punches 54 and 56. The briquette 140 thusobtained is then placed in a conventional sintering oven and sintered ina protective atmosphere such as hydrogen at conventional sintering timesand temperatures well known to those skilled in the powder metallurgyart. The workpiece upon removal from the sintering oven after sinteringis the inner component 126 of the inner race or cone 122 shown in FIG.3.

The outer component 128 of the inner race 122 is similarly 'formed (FIG.2) by placing a charge of high-performance powdered alloy metal suitablefor forming the desired compact or briquette 170, such as has beendescribed more fully above, in the generally frusto-conical die cavity172 in a briquetting die 174, generally similar to the briquetting die152 of FIG. 1 and having cylindrical upper and lower bores 176 and 178respectively joined by a frusto-conical bore 180 and an annular shoulder182 connecting the latter to the cylindrical bore 176. Reciprocablymounted in the upper and lower cylindrical bores 176 and 178 are anouter upper tubular punch 184 and a lower tubular punch 186.Reciprocably mounted within the upper and lower bores 188 and 190 of theouter upper punch 184 and lower punch 186 respectively is an inner upperpunch 192 (FIG. 2) having upper and lower cylindrical portions 194 and196) interconnected by a frusto-conical portion 198. The smallerdiameter cylindrical portion 196 serves as a nose portion when the innerupper punch 192 is raised together with the outer punch 184 so as topermit filling of the die cavity 172 without permitting the powder inthe charge placed therein to drop into the otherwise open bore 190within the lower tubular punch 186.

In making the outer component 26, the outer upper tubular punch 84 isretracted upward so as to uncover the die cavity 172. The die cavity 172is then filled with the charge of highperformance alloy powder,whereupon the outer upper punch 184 is moved downward and the lowertubular punch 186 is moved upward so as to compress the powdered alloycharge between their respective opposing annular end surfaces 200 and202 to form the compact or briquette 170. The tubular outer upper punch184 is then retracted upward, together with the inner upper punch 192and the lower tubular punch 186 is at the same time moved upward toeject the thus-formed compact 170 from the die cavity 172. This compact170 is then sintered in the same manner as described above for that ofthe inner component 126, thereby becoming the outer component 128. Thesintered inner component 126 of base metal is then forced into theinterior of the sintered high-performance alloy outer component 128 in aforging operation. The resulting composite blank, generally designated204, is then ground externally from the contour shown in dotted lines inFIG. 4 to the contour shown in solid lines therein so as to produce theannular roller path groove 206, whereupon the blank 204 becomes thefinished inner race or cone 122.

In FIGS. 11 to 14 inclusive there is shown the formation of thecomposite outer race 124 for the heavy-duty tapered roller bearing unit120 shown in FIG. 16. The method of making the outer race or cup 124 isdisclosed and claimed in our co-pending application, Ser. No. 95,310filed Dec. 4, 1970 for Composite Heavy-Duty Machine Element and Methodof Making the Same. It is briefly described here for the sake ofcompleteness and by reason of the fact that an outer race or cup isessential to a tapered roller bearing unit.

The outer component 124 is formed in either of two ways, the first beingshown in FIGS. 11 and 12 and the second in FIGS. 13 and 14. In FIGS. 11and 12, a composite sintered powdered metal blank 210 is made by placinga tubular divider (not shown) in the annular die cavity of aconventional briquetting press between its core rod and its outer wallat the place where the junction 212 between the high-performancesintered metal alloy inner component 214 and the low performancesintered powdered metal outer component 216 is to be located. Theoperator now fills the inner zone of the die cavity withhigh-performance powdered metal alloy of the type described above, thenfills the outer zone with low-performance powdered metal, such aspowdered iron, and then withdraws the tubular divider. He then operatesthe briquetting press to compress the two powders so that they form acompact or briquette. The latter is then placed in a sintering oven andsintered, whereupon it becomes the blank 210 with the high performancesintered powdered metal alloy inner component 214 and the lowperformance sintered powdered metal outer component 216 firmly andinseparably bonded to one another.

The composite sintered powdered metal blank 210 thus produced is thenpreferably heated to a warm temperature between 800 F. and 1,375 F. orto a hot temperature of 1,375 F. to 2,300 F. and forged into its finalshape 124 in a forging press 220 having an annular die cavity 222. Thedie cavity 22 forms the counterbore of a bore 224 into which the reduceddiameter nose portion 226 of a forging punch 228 extends. The forgingpunch punch 228 includes an upper large diameter portion 230 and afrusto-conical portion 232 extending between the large diameter portion230 and the small diameter portion 226. The large diameter portion 230is movable into and out of the cylindrical bore portion 234 of the diecavity 222, which has an annular shoulder 236 extending from the smalldiameter bore 224 to the larger diameter bore 234 which in turn opensinto a slightly larger diameter counterbore 238.

With the forging punch 228 in its raised or retracted position, thethus-heated composite sintered powdered metal blank 210 is dropped intothe die cavity 222 of the forging press 220. The forging punch 228 isthen brought downward upon the heated blank 210, such as by movingdownward the platen (not shown) to which the forging punch 228 isattached, thereby deforming the blank 210, shown in dotted lines in FIG.12, into the final shape of approximately triangular cross-section shownin solid lines in FIGS. 12 and 16,

infitthe composite sintered wdered metal outer race or cup 1 from anannular blank 0 shown in FIG. 13. The annular blank 240 is also producedin the die cavity of a conventional briquetting press (not shown), andconsists of an annular lower sintered powdered metal portion 242 of lowperformance metal, such as powdered iron, and above it an annular uppersintered powdered metal portion 244 of high-performance metal alloy,such as described above firmly and inseparably bonded to one another.The method of producing the blank 240 is generally similar to thatdescribed above in connection with the blank 210 of FIGS. 11 and 12,except that the tubular separator is not used. Instead, the operatorplaces in the annular die cavity a charge of low performance powderedbase metal, such as powdered iron, and afterward superimposed upon it alayer of high-performance powdered metal alloy, whereupon thebriquetting press compresses the thus-superimposed powders into acompact or briquette which, after sintering in a conventional sinteringpress, preferably in a protective atmosphere, such as hydrogen, becomesthe composite blank 240.

The composite blank 240 is now heated to either of the temperatureranges mentioned above in connection with the blank 210 and then forgedinto its final shape 124 in the forging press 250. The latter is similarin construction and operation to the forging press 220, hence similarparts are designated with the same reference numerals, except that aninclined annular shoulder 252 extends from the upper counterbore 238 tothe cylindrical portion 234 of the lower counterbore 222. With theforging punch 228 in its raised or retracted position, the thus-heatedsintered powdered metal blank 240 is dropped into the die cavity 222 ofthe forging press 220, whereupon the forging punch 228 is moved downwardinto the die cavity 222, thereby deforming the blank 240 from the dottedline position shown in FIG. 14 to the solid line position shown in FIG.16, thereby producing the composite outer race or cup 124. The latter isthen ejected from the die cavity 222.

I claim:

1. A method of making a composite heavy-duty mechanism element,comprising confining an annular mass of low-performance metal particlesin an annular enclosure,

confining an annular mass of high-performance powdered alloy particlesin an annular enclosure having a side wall surface configured to impartto said high perfonnance mass a surface adapted to mate with a surfaceof said lowperformance mass,

compacting each mass separately in its respective annular enclosure,

sintering each such compacted mass,

and pressing said masses into particle-interlocking mating engagementsubsequent to said sintering.

2. A method, according to claim 1, wherein the high-performance alloyparticle mass is disposed externally of the lowperformance metalparticle mass during said pressing step.

3. A method, according to claim 1, including forming teeth in thehigh-performance alloy particle mass.

4. A method, according to claim 1, including forming an annular rollerpath on the high-performance alloy particle mass.

5. A method, according to claim 3, including inclining said teethrelatively to the axis of said mass during formation of said teeth.

6. A method, according to claim 4, including recessing said roller pathinto said high-performance alloy particle mass during formation of saidroller path into said high-performance alloy particle mass duringformation of said roller path.

a m a r

1. A method of making a composite heavy-duty mechanism element,comprising confining an annular mass of low-performance metal particlesin an annular enclosure, confining an annular mass of high-performancepowdered alloy particles in an annular enclosure having a side wallsurface configured to impart to said high performance mass a surfaceadapted to mate with a surface of said low-performance mass, compactingeach mass separately in its respective annular enclosure, sintering eachsuch compacted mass, and pressing said masses into particle-interlockingmating engagement subsequent to said sintering.
 2. A method, accordingto claim 1, wherein the high-performance alloy particle mass is disposedexternally of the low-performance metal particle mass during saidpressing step.
 3. A method, according to claim 1, including formingteeth in the high-performance alloy particle mass.
 4. A method,according to claim 1, including forming an annular roller path on thehigh-performance alloy particle mass.
 5. A method, according to claim 3,including inclining said teeth relatively to the axis of said massduring formation of said teeth.
 6. A method, according to claim 4,including recessing said roller path into said high-performance alloyparticle mass during formation of said roller path into saidhigh-performance alloy particle mass during formation of said rollerpath.